1. Field of the Invention
The invention relates to a fixture for threading-on and simultaneously turning the nut means of several screw bolts, necked-down screws, tie rods or the like. More particularly, the invention relates to a fixture wherein a support ring is provided with recesses each for receiving a nut means and its associated screw bolts, and wherein separate turning units functioning as reversible electric motors are fastened to the ring for turning each nut means and a hydraulically tensioning means is provided for stretching each screw bolt.
2. Description of the Prior Art
A fixture of the above-type is disclosed in German Offenlegungsschrift No. 2,258,859. In the aforesaid fixture, the nut means used for tightening and pre-tensioning each screw bolt is provided with external teeth with which a pinion meshes, the latter pinion being driven by an electric motor via a reduction gear. These teeth weaken the nut means and, in addition, cause the force required to rotate the nut means to be applied only at one point along the circumference thereof. As a result, internal thread damage to the nut means can occur, due to tilting moments and one-sided radial forces.
It is an object of the present invention to provide an improved fixture of the above-type wherein threading-on and screwing or unscrewing of the nut means is carried out with a more favorable force-flow.